Receive the latest national-international updates in your inbox

Erik Grosof with the National Transportation Safety Board provides an update on the investigation into a deadly hot air balloon crash in Lockhart, Texas, on July 30, 2016. (Published Saturday, July 30, 2016)

Two of the 16 or more people killed in Saturday's hot air balloon crash near Austin, Texas — one of the deadliest in U.S. history — were identified by their brother Sunday, and remembered as "incredible human beings."

Matt and Sunday Rowan, both 34, were married within the last year, according to Matt's older brother, Joshua Rowan. Officials have not yet released the names of the deceased, but Joshua Rowan told NBC News about his brother and sister-in-law on Sunday, hoping to share with the world what good people they are.

"They’re going to be incredibly missed. They made a difference in so many people’s lives," he said.

Matt Rowan was a professor who had just started working at an army hospital burns trial unit. He believed his work would help soldiers who have been burned, according to his brother, himself an Iraq veteran.

The National Transportation Safety Board said Sunday at least 16 people died, but added that investigators are still trying to determine the exact number of passengers. A small team of NTSB investigators was already at the site Sunday morning, an official said, with more on the way.

"The identification of the victims will be a long process according to the NTSB and the medical professionals," according to a news release from the Caldwell County Sheriff's Office. The FAA and FBI are also investigating the crash.

Officials Believe No Survivors in Texas Balloon Crash

Authorities say they believe there were no survivors when a hot air balloon carrying at least 16 people caught fire an crashed near Austin Saturday. (Published Saturday, July 30, 2016)

It wasn't known if the operator of the hot air balloon — whom authorities haven't identified, or the pilot — filed a passenger manifest before taking off, an NTSB official said Sunday.

NBC News confirmed the balloon was operated by Heart of Texas Hot Air Balloon Rides through the company's Facebook page. The owner of the account verified that it was the company's balloon that went down.

Skip Nichols identifies himself on his Facebook page as the chief pilot of Heart of Texas and pictures posted by him are on the business' Facebook page. His roommate told NBC Dallas-Fort Worth that Nichols was the pilot of the balloon, but authorities had not confirmed that information.